Texture Painting issue - colour randomly showing on wrong faces
You need to:

Unwrap again, your islands are probably overlapping, choose the Smart UV Project option with a bit of Island Margin (0.03).
Put a bit of bleeding in the N panel &gt; Tool &gt; Options so that the paint correctly covers the islands.
Your image is currently 1024 pixels large, depending on what kind of shots you want to do it might be a bit too small, so maybe increase the size